JP 3-50 National Search and Rescue Manual Vol I - US Navy

TABLE 5-14. Environmental Limitations and Multisensor Search
Environmental Visual Radar Infrared
Limitation
Darkness Very limited Short- and long- Short-range
detection range target target detection/
capability detection, but identification of
no identification long-range radar
targets after
closing
Poor visibility Detection and Short- and long- May extend limits
(daylight) identification range target of visibility
to limit of detection, but when haze limits
visibility no identification detection by
naked eye
High sea state Reduced Detection of Short-range
effectiveness, medium/large target detection/
but some targets only identification
ability to
distinguish Many false Better than
target from targets visual search
whitecaps only at night or
with high thermal
contrast target
messages, C should normally be used rather than POD to indicate the
coverage required. The relationship between sweep width and track
spacing is:
Coverage Factor (C) = Sweep width (W)
Track spacing (S)
Sweep width and track spacing are measured in the same units
(nautical miles or yards), and C is dimensionless. Higher coverage
factors indicate more thorough coverage. Coverage factors of 0.5 and
1.0 are compared in Figure 5-18. If coverage cannot be compromised,
then additional SRUs should be found, the area decreased, the time
increased, or SRU speed increased.
537 Probability of Detection
A. Probability of Detection (POD) is the probability that the
search object will be detected provided it is in the area searched. It
is a function of coverage and the total number of searches in an area,
and describes the effectiveness of a single search or the cumulative
effectiveness of multiple searches.
B. For any search of an area, the SMC may specify a desired POD
and determine the coverage factor accordingly, or, if there are
constraints on C, the SMC may have to settle for an attainable POD.